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cc65/libsrc/pet/crt0.s
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which included commits to RCS files with non-trunk default branches.


git-svn-id: svn://svn.cc65.org/cc65/trunk@3 b7a2c559-68d2-44c3-8de9-860c34a00d81
2000-05-28 13:40:48 +00:00

126 lines
2.3 KiB
ArmAsm

;
; Startup code for cc65 (PET version)
;
; This must be the *first* file on the linker command line
;
.export _exit
.import __hinit, initconio, zerobss, push0, doatexit
.import _main
.include "pet.inc"
.include "../cbm/cbm.inc"
; ------------------------------------------------------------------------
; Define and export the ZP variables for the C64 runtime
.exportzp sp, sreg, regsave
.exportzp ptr1, ptr2, ptr3, ptr4
.exportzp tmp1, tmp2, tmp3, tmp4
.exportzp regbank, zpspace
sp = $02 ; stack pointer
sreg = $04 ; secondary register/high 16 bit for longs
regsave = $06 ; slot to save/restore (E)AX into
ptr1 = $0A ;
ptr2 = $0C
ptr3 = $0E
ptr4 = $10
tmp1 = $12
tmp2 = $13
tmp3 = $14
tmp4 = $15
regbank = $16 ; 6 byte register bank
zpspace = $1A ; Zero page space allocated
; ------------------------------------------------------------------------
; BASIC header with a SYS call
.org $3FF
.word Head ; Load address
Head: .word @Next
.word 1000 ; Line number
.byte $9E,"1037" ; SYS 1037
.byte $00 ; End of BASIC line
@Next: .word 0 ; BASIC end marker
.reloc
; ------------------------------------------------------------------------
; Actual code
ldy #zpspace-1
L1: lda sp,y
sta zpsave,y ; Save the zero page locations we need
dey
bpl L1
; Close open files
jsr CLRCH
; Switch to second charset
lda #14
; sta $E84C ; See PET FAQ
jsr BSOUT
; Clear the BSS data
jsr zerobss
; Save system stuff and setup the stack
tsx
stx spsave ; Save the system stack ptr
lda MEMSIZE
sta sp
lda MEMSIZE+1
sta sp+1 ; Set argument stack ptr
; Initialize the heap
jsr __hinit
; Initialize conio stuff
jsr initconio
; Pass an empty command line
jsr push0 ; argc
jsr push0 ; argv
ldy #4 ; Argument size
jsr _main ; call the users code
; fall thru to exit...
_exit: jsr doatexit ; call exit functions
ldx spsave
txs ; Restore stack pointer
; Copy back the zero page stuff
ldy #zpspace-1
L2: lda zpsave,y
sta sp,y
dey
bpl L2
; Back to basic
rts
.data
zpsave: .res zpspace
.bss
spsave: .res 1
mmusave:.res 1